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RE: giving `setq-local' the same signature as `setq'

From: Drew Adams
Subject: RE: giving `setq-local' the same signature as `setq'
Date: Thu, 19 Mar 2015 10:25:19 -0700 (PDT)

> > You can do the same for `let*', if you like:
> > (let ((foo  fooval))
> >   (let ((phlop  phlopval))
> >     (let ((toto  totoval))
> >       ...)))
> Now you've just lead yourself into a trap. This is similar to
> one-var-per-setq:
> (let* ((foo fooval)
>        (phlop phlopval)
>        (toto totoval))
>   ...)

No, one var per `let' would be as I showed it - 3 `let's for 3 bindings.

Using `let*' with multiple vars is analogous to using `setq' with multiple
vars.  `setq' assigns and `let*' binds, but they both let you give values
to multiple variables.  Or to only one variable at a time - your choice.

> This is similar to multi-var-per-setq:
> (let* (foo fooval
>        phlop phlopval
>        toto totoval)
>   ...)

No, that is simply malformed code.

> >> It also gives an anchor to quickly navigate to the variable
> >> to get its value.
> >
> > How so?  Please elaborate.
> With C-M-n and C-M-p you can navigate to the big fat paren by which the
> variable resides (after setq).


> >> In a setq list of 10 items, by item 5 it is already unclear which is the
> >> variable and which is the value.  In my opinion, it's not worth
> >> complicating the code maintenance just to save a few chars.
> >
> > This is why it is good that you have the choice.
> You're wrong here. I don't have the choice. Just yesterday I was debugging
> my AUCTEX config. It wasn't pleasant to navigate 5-variable setq
> statements, some of which took the whole page.

That problem is independent of this discussion, unless you are referring
to the convenience of your using `C-M-p' to move to individual assignments.

One can write bad code, with 473 `setq's in a row or with a single `setq'
that has 473 assignments.  Being able to group assignments in a single
`setq' does not require anyone to use many assignments in a row.

> > I find it clearer to let `setq' do the grouping, instead of implicit or
> > explicit `progn'.  But I put each var & value pair on a separate line:
> >
> > (setq foo    fooval
> >       phlop  phlopval  ; Maybe this one needs a comment.
> >       toto   totoval)
> >
> > I don't do this to save characters (e.g. for typing).  I do it to make
> > the code clearer and maintenance less error prone and easier.  For me,
> > at least.
> Imagine that you want to comment out `phlop phlopval', which is a
> multi-line statement. If it was bounded by parens, you could do it in an
> easy and error-free way. Otherwise, you have to manually select the region.

Actually, `phlop phlopval' is a single line, and can be commented out simply.

But I take your point.  Yes, the style I prefer can mean extra typing.
To me it's worth it, for the sake of clearer code (IMO).  But you don't
need to write code the way I prefer.  And you don't need to maintain my

If you work with a team to create and maintain code, then it can help to
decide what the team prefers, in terms of coding style.  That's not
limited to this discussion about `setq'.

What is germain to this discussion is that different teams can choose
what they want, wrt using separate `setq's for multiple assignments.

What you propose is that for the sake of "consistency" there must be,
in effect, only one team: the choice should be made for Emacs Lisp as
a whole, instead of letting those who use it decide.

I prefer that Emacs Lisp be consistent with, well, LISP in this regard.

Multiple assignments for `setq' have been around since the 60s in Lisp
(but no, they were not in Lisp 1.5).  At least two of us like it that way.

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